Ever since Warren Buffett and Bill and Melinda Gates formed the Giving Pledge in 2010, enlisting American billionaires to commit at least half of their wealth to charity, one question has hovered: why did the founders focus solely on domestic fortunes? The reason, Buffett now tells Forbes: “I felt we had our hands full in the U.S.”

That changes later today when the Gates Foundation will announce that the Giving Pledge has expanded its reach globally, starting with 12 non-U.S. signatories from 8 different countries, from the U.K.’s Richard Branson to Malaysia's Vincent Tan. These new “Pledgers” will swell the group’s total to 105. Buffett credits Bill Gates for the international expansion, likening his frequent globetrotting to a “trade mission” which has now accelerated the global philanthropic half-life “by a generation.”

It wasn’t originally an easy sell. Shortly after launching the Giving Pledge, Gates and Buffett held group dinners with moguls in countries like China, India and Saudi Arabia, and faced cultural hurdles that ranged from civic modesty to perpetuating family dynasties. Often something was lost in translation. Industrialist Victor Pinchuk, Ukraine’s second-richest person and one of the dozen new Pledgers as of today, tells Forbes that he originally misunderstood the concept’s idea. Specifically, he believed that it contractually required him to give to specific charities or foundations, versus morally binding him to donate at least half his wealth during his lifetime, or at his death, to causes he saw fit.

Pinchuk says that Eli Broad, an early Pledger, corrected his thinking in September at the Clinton Global Initiative, and then Gates sealed the deal at World Economic Forum at Davos last month, via “a very soft” touch, where he conveyed this essence of the pledge and answered any questions the Ukrainian had.

“The decision was already inside me,” says Pinchuk, who Forbes currently estimates is worth $4.2 billion. “Philanthropy is a very important part of my life. In the 21st century, to be seen as a contemporary businessman, solving global problems is as important as making profits.”

Each of these people, according to Buffett, isn’t just committing to what in aggregate totals more than $10 billion of charitable good. The Giving Pledge is less about the financial promise than a public statement meant to inspire others, and a network that compares notes, especially at the group’s annual meeting in May, in order to increase the efficacy of their charitable endeavors.

Buffett says that this group of new Pledgers was specifically responsible for advocating the movement in their respective countries, serving both as role models and recruiters, with the goal of creating local ripple effects. One new Pledger, South Africa’s Mostepe, made the trek to Omaha for a one-on-one with Buffett, telling the Oracle that the Pledge had become increasingly top of mind among the ultra-wealthy of his country. “If we can get to South Africa,” says Buffett, “we can get to a lot of places.”

To that end, Pinchuk says that Gates has already asked him who else from Eastern Europe might also be a candidate. “Frankly speaking, I have some names in mind who potentially will be interested to formally join this,” says Pinchuk. “[Gates and Buffett] will be surprised how many conversations I’ve had from big businessmen in this part of the world.”

The ultimate goal, Buffett adds, is to get the Giving Pledge into every part of the world. “We always hoped that the U.S. would be an example,” says Buffett. “We’ve exported a lot of good ideas from this country.” Representative democracy. Free-market capitalism. If the Gateses and Buffett sign up most of the 1,226 global billionaires that Forbes has identified, perhaps entrepreneurial philanthropy will carry the same all-American connotation.

I am the editor of Forbes Magazine, and believe strongly that entrepreneurial capitalism and market-based thinking can solve the world's problems. This is my second stint at Forbes -- between 1991 and 1997, I was a reporter, a staff writer (five cover stories), associate edi...